The present invention relates in general to laboratory simulation devices which are used for testing materials and components in a laboratory environment in order to verify or predict how the materials and components will behave in actual use. More particularly, the present invention relates to a wear simulator for piston rings and cylinder liners wherein an operating engine environment is simulated and data on friction forces, wear and friction coefficients is developed based upon different speeds, loads, materials, temperatures and lubricants.
Future advanced diesel engines are expected to require lubricants, cylinders liners, and piston rings that can withstand higher temperatures under highly loaded conditions, with minimal lubrication at the sliding surfaces. Screening new materials and designs in an engine is very expensive and time consuming. To expedite screening, a high-temperature wear simulator has been developed. The wear simulator of the present invention is a bench type fixture capable of testing potential lubricant, liner and ring combinations under simulated engine conditions of speed, load, temperature and lubrication.
Earlier work in this area was orally presented at the 1987 Coatings for Advanced Heat Engines Workshop which was part of the U.S. Department of Energy Conference in Castine, Maine from July 27 to July 30, 1987.
One oral presentation by R. J. Slone et al. was entitled "Upper Cylinder Wear Simulation in Heavy Duty Diesel Engines." This presentation discussed the results of wear tests including testers which attempted to demonstrate the effects of lubrication, coatings, loadings and speeds. The present invention was not mentioned or discussed, and in fact the present invention was being developed and researched in order to overcome some of the deficiencies and drawbacks of the testers which were reviewed in this presentation.
Another oral presentation during this Department of Energy conference by M. G. Naylor was entitled "Development of Advanced Diesel Wear Coatings." This presentation discussed the characteristics of coatings used on the wear components of diesel engines. The specific wear testers used for the tests were not discussed.
While the earlier work of these two oral presentations identifies results, needs and concerns, it does not offer answers or solutions to certain deficiencies and drawbacks. The present invention provides these answers and solutions in an automated device which is used in a controlled environment and which uses actual components, piston rings, and portions of actual components, cylinder liners. The present invention is able to simulate the most stressful part (top and bottom piston ring reversal) of the piston ring cycle of a reciprocating engine. Other wear testers typically use special pieces made up for use in the tester and thereby lose some of its simulation value. The present invention provides a more reliable and more valid set of test results. The automated nature of the present invention enables the test to be initially set up with a wide range of settable conditions such as stroke, cycle rate, type of lubricant, temperature, etc. and then run automatically for the data gathering and processing phase. The wear simulator of the present invention has successfully demonstrated piston ring and cylinder liner wear rates which closely correlate to actual engine data.